Synthesis of spirocyclic azacycles from the cyclization of furan tethered N-acyliminium ions
作者:Sudhir R. Shengule、Anthony Willis、Stephen G. Pyne
DOI:10.1016/j.tet.2011.11.055
日期:2012.1
intermolecular reaction between 2a or 2b, via the nucleophilic C5 furan carbon, and their corresponding N-acyliminium ion intermediates. When the furan C5 position of 2b was blocked by substitution with bromine then TFA or Sc(OTf)3 catalysed cyclization reactions gave a spirotricyclic product (a 5-6-6-tricycle) in a highly diastereoselective manner. Cyclization of the analogous C5-Br-furan-pyrrolidone 29 with